1 /************************************************************** 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, 14 * software distributed under the License is distributed on an 15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16 * KIND, either express or implied. See the License for the 17 * specific language governing permissions and limitations 18 * under the License. 19 * 20 *************************************************************/ 21 22 23 24 #ifndef _BGFX_TOOLS_KEYSTOPLERP_HXX 25 #define _BGFX_TOOLS_KEYSTOPLERP_HXX 26 27 #include <basegfx/numeric/ftools.hxx> 28 #include <vector> 29 #include <basegfx/basegfxdllapi.h> 30 31 namespace com{ namespace sun{ namespace star{ namespace uno { 32 template<typename T> class Sequence; 33 }}}} 34 35 namespace basegfx 36 { 37 namespace tools 38 { 39 /** Lerp in a vector of key stops 40 41 This class holds a key stop vector and provides the 42 functionality to lerp inside it. Useful e.g. for 43 multi-stop gradients, or the SMIL key time activity. 44 45 For those, given a global [0,1] lerp alpha, one need to 46 find the suitable bucket index from key stop vector, and 47 then calculate the relative alpha between the two buckets 48 found. 49 */ 50 class BASEGFX_DLLPUBLIC KeyStopLerp 51 { 52 public: 53 typedef std::pair<std::ptrdiff_t,double> ResultType; 54 55 /** Create lerper with given vector of stops 56 57 @param rKeyStops 58 59 Vector of stops, must contain at least two elements 60 (though preferably more, otherwise you probably don't 61 need key stop lerping in the first place). All 62 elements must be of monotonically increasing value. 63 */ 64 explicit KeyStopLerp( const std::vector<double>& rKeyStops ); 65 66 /** Create lerper with given sequence of stops 67 68 @param rKeyStops 69 70 Sequence of stops, must contain at least two elements 71 (though preferably more, otherwise you probably don't 72 need key stop lerping in the first place). All 73 elements must be of monotonically increasing value. 74 */ 75 explicit KeyStopLerp( const ::com::sun::star::uno::Sequence<double>& rKeyStops ); 76 77 /** Find two nearest bucket index & interpolate 78 79 @param fAlpha 80 Find bucket index i, with keyStops[i] < fAlpha <= 81 keyStops[i+1]. Return new alpha value in [0,1), 82 proportional to fAlpha's position between keyStops[i] 83 and keyStops[i+1] 84 */ 85 ResultType lerp(double fAlpha) const; 86 87 private: 88 std::vector<double> maKeyStops; 89 mutable std::ptrdiff_t mnLastIndex; 90 }; 91 } 92 } 93 94 #endif 95